County profile · official public datasets

Marshall County, IL

155 public highway bridges tracked in the FHWA National Bridge Inventory: 42.6% rated Good, 44.5% Fair, 12.9% Poor.

155
Public bridges: 42.6%
Good condition: 12.9%
Poor condition

The verdict

According to the Federal Highway Administration's 2024 National Bridge Inventory.

Marshall County pairs a higher-than-median Poor-condition share among rated counties in the state with a newer average build year than the state inventory.

85th
of 102 on Poor share: 12.9%
Poor-condition share: 155
public highway bridges: 1984
avg year built

Poor is an FHWA condition category from the lowest applicable component rating (4 or below), not a live crossing-safety or closure decision. Rankings cover counties with at least five public highway bridges.

Marshall County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Marshall County ranks #85 of 102 Illinois counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 12.9%). Marshall County, Illinois contains 155 public highway bridges. Roughly 42.6% are rated “Good,” 44.5% “Fair,” and 12.9% “Poor.” Poor means the lowest applicable deck, superstructure, substructure, or culvert rating is 4 or below on the 0–9 NBI scale. It is a condition category, not a live safety or closure decision.

Responsible agencies inspect covered bridges on risk-based intervals under current NBIS rules and submit inventory data to FHWA annually. The list below shows every NBI-tracked bridge in the county. Use the “Sort by” controls to change the ordering, and click any row for its reported inspection date, traffic count, and condition fields.

Source: FHWA National Bridge Inventory. See methodology for full definitions.

Total bridges

155

Public highway bridges in Marshall County

Good condition

42.6%

66 of 155 rated 7-9

Fair condition

44.5%

69 of 155 rated 5-6

Poor condition

12.9%

20 of 155 rated 4 or below

In-state Poor-share rank

#85 of 102

Among Illinois counties with 5+ bridges, lower share ranks better

Condition distribution

Share of 155 NBI-tracked bridges by lowest applicable component rating.

Good

42.6% (66)

Fair

44.5% (69)

Poor

12.9% (20)

Marshall County's Poor-condition bridges carry 11,220 vehicle crossings a day

That is 7.5% of the county's reported daily bridge traffic on 12.9% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 561 crossings a day against 270 for a Good-condition one. A Poor rating is a condition category, not a closure or a live safety judgement; it means the lowest applicable component rating is 4 or below.

Computed over the 155 of 155 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

26.5% of Marshall County's bridges have passed the 50-year mark

41 of the 155 bridges with a recorded construction year were built in 1974 or earlier. Age alone is not a defect: a well-maintained older bridge can rate Good, and 42.6% of this county's inventory does. Even so, this older cohort is the population from which future Poor ratings are drawn, which is why the age profile below matters alongside the condition split above.

Cutoff derives from the 2024 release year minus a 50-year design life. Source: FHWA National Bridge Inventory, 2024 release.

One structure carries 62.4% of the county's Poor-condition bridge traffic

ILL 17 over ILL RIVER, built 1939, carries 7,000 vehicles a day, the most of any Poor-rated structure here. The county's Poor-condition exposure is concentrated rather than evenly spread, so the 20-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 11,220 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1920s

3
1930s

7
1940s

1
1950s

2
1960s

14
1970s

30
1980s

27
1990s

32
2000s

26
2010s

12
2020s

1

What this shows Construction peaked in the 1990s, when 32 of the county's bridges still in the inventory were built, which is 20.6% of those with a recorded year. That cohort is now 25 to 34 years old in the 2024 inventory. Its average build year is 1984, 5 years newer than the Illinois average of 1979.

How Marshall County compares with Illinois's closest counties by inventory size

The 5 Illinois counties nearest Marshall County in number of bridges, with their condition splits. Its 12.9% Poor share is the 6th-lowest of these 6. Its average build year of 1984 against a peer-group mean of 1979 is 5 years newer.

Showing the 5 closest of 101 Illinois counties eligible for comparison.

Bridge inventory size and condition shares for Marshall County and the 5 Illinois counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Mercer County	163	50.9%	42.3%	6.7%	1982
Bond County	162	45.7%	46.3%	8%	1971
Greene County	162	51.9%	42.6%	5.6%	1981
Marshall County (this page)	155	42.6%	44.5%	12.9%	1984
Richland County	151	68.2%	26.5%	5.3%	1979
Randolph County	149	59.7%	32.9%	7.4%	1981

Each share is of that county's own total tracked bridges; peers are the counties with 5 or more bridges whose inventory size is closest to Marshall County's. Source: FHWA National Bridge Inventory, 2024 release.

Nationwide counties with similar inventory size or average build year

Two NBI-derived peer sets for Marshall County, both outside Illinois so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside IL (155 bridges here).

Clarke County, AL · 155 bridges
Tallahatchie County, MS · 155 bridges
Haskell County, OK · 155 bridges
Clatsop County, OR · 155 bridges

Similar average build year

Nearest mean year-built outside IL (1984 here).

Hennepin County, MN · avg 1984 · 936 bridges
Duval County, FL · avg 1984 · 831 bridges
El Paso County, CO · avg 1984 · 686 bridges
Bell County, TX · avg 1984 · 660 bridges

Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.

All 155 Good 66 Fair 69 Poor 20

Fair-condition bridges (69)

Sort:

Marshall County Bridge Snapshot

Condition distribution

Marshall County's Poor-condition bridges carry 11,220 vehicle crossings a day

26.5% of Marshall County's bridges have passed the 50-year mark

One structure carries 62.4% of the county's Poor-condition bridge traffic

How Marshall County compares with Illinois's closest counties by inventory size

Nationwide counties with similar inventory size or average build year

Similar inventory size

Similar average build year

Fair-condition bridges (69)

TR 22 (TH-R65)

WASHINGTON ST

TR 112 (TH-S44)

TR 3 (TH-C52)

FAS 371 (CH S-32)

TR 8 (TH-R56)

TR 48 (TH-S18)

TR 69A (TH-C65)

TR 102A (TH-S40)

TR 126 (TH-S48)

TR 75 (TH-C69)

TR 85 (TH-C69)

TR 12 (TH-R63)

TR 69A (TH-C65)

TR 126 (TH-S48)

TR 149 (TH-D18)

TR 140C (TH-S55)

TR 20 (TH-R65)

TR 130B (TH-S51)

TR 13 (TH-C55)

TR 98

TR 144 (TH-S57)

TR 77 (TH-C68)

TR 86 (TH-S34)

TR 33 (TH-C60)

TR 96 (TH-S38)

TR 150 (TH-S60)

TR 37 (TH-C60)

TR 146 (TH-S 59)

TR 147 (TH-D17)

TR 68 (TH-S 27)

TR 68 (TH-S27)

TR 42 (TH-S17)

TR 42 (TH-S17)

TR 24 (TH-R66)

THENIUS ROAD

CH 13 (CH-R60)

FAS 369 (TH-D12)

ILL 18

ILL 89

ILL. 26

FAS 369 (400 N)

CH 14

IL 26

ILL 18

I-39/US 51(SB)

TR 104A (TH-S65)

I-39/US 51 SB

I-39/US 51 NB

I-39/US 51(SB)

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